Nozzles, known to produce a vacuum condition via a venturi effect, have long been used to combine certain liquids for purposes of producing various liquid mixtures. See, for example, U.S. Pat. No. 1,382,684 to Shimper as well as U.S. Pat. No. 2,228,705 to Olson.
When it is desirable to combine liquids in predetermined ratioed amounts, on the other hand, nozzles are generally not the liquid-mixing devices of choice, because variations in vacuum can affect individual flowrates of such liquids into the nozzle. As a result, other types of liquid-mixing devices have in the past been used for purposes of combining liquids in predetermined ratioed amounts. See, for example, U.S. Pat. No. 2,736,466 to Rodth; U.S. Pat. No. 2,796,196 to Ortner; and U.S. Pat. No. 4,079,861 to Brown. Unfortunately, liquid-mixing devices of these sorts are generally inherently more complex than nozzles, both in design and in operation.
From a manufacturing standpoint as well as from a "use" standpoint, simplicity in design and operation are generally desirable because of the various cost efficiencies which are attendant thereto. Indeed, certain recent advances in the nozzle art are disclosed and discussed in U.S. Pat. Nos. 4,406,406 and 4,545,535, both to Knapp.
In general, the '406 and '535 Knapp patents each disclose a liquid-metering apparatus as well as a liquid-dispensing apparatus for spraying plants with so-called "micro-dispensing amounts" of certain desired liquids. In particular, the '406 and '535 Knapp patents each disclose a liquid-metering apparatus as well as a liquid-dispensing apparatus for combining between 200 parts to 4,000 parts of liquid concentrate with a million parts of water.
As a practical matter, considering only the concentrate, a range of 200 "parts" to 4000 "parts" is, in certain situations, overly narrow. Indeed, there are a number of applications where it would be desirable to operate in a relatively broader range, considering only the concentrate.
For example, there are a number of applications where it would be desirable to mix a liquid concentrate with a liquid diluent, within the concentrate-to-diluent ratio range of about 1:2 to about 1:1500.
Because of the above-mentioned design simplicity and attendant cost efficiencies, it would be highly desirable to utilize the venturi effect of a nozzle to combine fluids in precisely-ratioed amounts to produce various fluid mixtures.
Those skilled in the nozzle art well know, however, that nozzles which are designed in accordance with the principles of current technology are not able to reproducibly provide a desired liquid mixture, principally due to flow and/or pressure fluctuation of the so-called "prime mover" fluid through the nozzle.
Thus it would be even more desirable, after selecting a particular concentrate-to-diluent ratio, to be able to utilize nozzles to achieve a particular, desired concentrate-to-diluent ratio, for purposes of mixing fluids in predetermined precisely-ratioed amounts, with no more than about 10 percent volume variation occurring in the concentrate-to-diluent ratio that was selected initially.